By Ben Geman - 04/19/13 04:49 PM EDT
The role of gas in climate change has been the subject of debate in recent years as production, enabled by the technique called hydraulic fracturing, has boomed.
Gas produces much less carbon dioxide than coal when burned to produce electricity, and has helped drive down U.S. carbon emissions in recent years.
But leakage of the potent greenhouse gas methane at gas wells, processing and other stages of development has bred criticism of the fuel’s usefulness as a tool to fight climate change.
The new study, however, finds that overall “lifecycle” greenhouse gas emissions – that is, from drilling through electricity production – from Marcellus shale gas is 53 percent lower than coal in carbon-equivalent terms.
“The analysis employs the most extensive data set of any [lifecycle assessment] of shale gas to date, encompassing data from actual gas production and power generation operations,” the study states.
The lifecycle emissions from natural gas are generating increasing attention as production booms and gas increasingly eats into coal’s once-dominant share of U.S. power production.
The World Resources Institute (WRI), a respected environmental think tank, said in a major April report that total amounts of methane leakage are “unclear,” and that reductions are needed and can be achieved using proven technology.
It looked at use of gas for power and as a transportation fuel.
“Cutting methane leakage rates from natural gas systems to less than 1 percent of total production would ensure that the climate impacts of natural gas are lower than coal or diesel fuel over any time horizon,” a summary of the WRI paper states.
The industry group Energy In Depth lauded the study from the Exxon Mobil Research and Engineering Company.
The group is also highlighting the Environmental Protection Agency’s recent downward revision of the amount estimated methane leakage from natural gas development.
“Credible studies have consistently shown that claims of high methane emissions and enormous leaks are pure invention, and this latest study proves that,” Energy In Depth said in a statement.